Fathoming the mechanistic details of ShRK signaling in the interaction of Arabidopsis thaliana and the obligate biotrophic oomycete Hyaloperonospora arabidopsidis

植物与环境不断交换，但在面临不利条件时却无法移动。受体激酶（RKs）由连接到细胞质激酶结构域的细胞质外传感器结构域组成，并且将细胞的外部与内部连接。因此，RKs使植物能够翻译细胞外信号穿过质膜，并启动特定的信号级联反应，以响应外源和内源性刺激。因此，这导致植物适应其环境，以克服不利的情况，如病原体攻击或营养缺乏。RKs的LRR-I家族的成员具有由富含亮氨酸的重复序列（LRR）随后是包含一个或两个完整或截短的马来凝集素基序的N-末端马来凝集素样结构域（MLD）组成的胞质外部分（MLD-LRR-RKs）。以前，我们确定了两个MLD-LRR-RKs，ShRK 1和ShRK 2，这涉及在专性生物营养卵菌的住宿和霜霉病的病原体阿拉伯透明霜霉病菌（Hpa）在拟南芥叶片。我们可以证明ShRK 1和ShRK 2参与了病原菌的繁殖成功，并有助于梨形吸器的形成。然而，到目前为止，MLD-LRR-RKs的确切信号传导机制，特别是ShRKs，仍然是模糊的。ShRKs如何影响卵菌发育和细胞信号传导是完全难以捉摸的。为了阐明MLD-LRR-RK信号传导和调控，我们将采用生物化学，遗传学和细胞生物学方法，并专注于ShRKs在拟南芥-Hpa相互作用中的作用。我们将研究不同ShRK模块参与信号转导及其对蛋白质调控的贡献，研究ShRK的时空调控，识别和表征直接ShRK相互作用，并检查Hpa感染期间ShRK介导的基因表达变化。有了这一点，我们将在一方面阐明的分子方面的Aromopsis Hpa协会，这将有助于理解和操纵这种有毒的植物微生物的相互作用。由于农业相关作物也会受到卵菌感染，导致产量损失，因此从长远来看，这项研究可能会成为可持续和面向未来的农业发展的一个重要方面。另一方面，我们将提供对MLD-LRR-RK信号传导和调节的总体见解，这将为未来重点研究这个非常有趣且研究不足的蛋白质家族所参与的不同过程铺平道路。

Plants are in continuous exchange with their environment, yet they are unable to move in case they face adverse conditions. Receptor kinases (RKs) consist of an extracytoplasmic sensor domain that is connected to a cytoplasmic kinase domain, and link the outside of a cell with the inside. Thereby RKs enable plants to translate extracellular cues across the plasma membrane and to initiate specific signaling cascades in response to exogenous and endogenous stimuli. Consequently, this results in the adaption of the plant to its’ environment to overcome unfavorable situations like pathogen attack or nutrient scarcities. Members of the LRR-I family of RKs possess an extracytoplasmic proportion composed of leucine-rich repeats (LRRs) followed by a N-terminal malectin-like domain (MLD) comprising one or two complete or truncated malectin motifs (MLD-LRR-RKs). Previously, we identified two MLD-LRR-RKs, ShRK1 and ShRK2, which are implicated in the accommodation of the obligate biotrophic oomycete and causing agent of downy mildew disease Hyaloperonospora arabidopsidis (Hpa) in Arabidopsis thaliana leaves. We could demonstrate that ShRK1 and ShRK2 are involved in the reproductive success of the pathogen and contribute to the formation of pyriform haustoria. To this day, the precise signaling mechanisms of MLD-LRR-RKs in general and ShRKs in particular are, however, still obscure. It is completely elusive how ShRKs impact oomycete development and cellular signaling. To shed light on MLD-LRR-RK signaling and regulation, we will employ biochemical, genetic, and cell biology approaches and focus on the role of ShRKs in the Arabidopsis-Hpa interaction. We will investigate the involvement of the different ShRK modules in signal transduction and their contribution to protein regulation, study the spatio-temporal regulation of ShRKs, identify and characterize direct ShRK interactors, and inspect ShRK-mediated changes in gene expression during Hpa infection. With this we will on the one hand shed light on the molecular aspects of the Arabidopsis-Hpa association, which will help to understand and manipulate this noxious plant-microbe interaction. As agriculturally relevant crops suffer from oomycete infection that causes yield loss as well, this research – in the long run - might constitute an important aspect in the development of a sustainable and future-oriented agriculture. On the other hand, we will provide insight into MLD-LRR-RK signaling and regulation in general, which will pave the way for future research focusing on the diverse processes this highly interesting and under-studied protein family is involved in.